Organometallics 1983,2, 843-845
a43
Assembling Capacity of P/N Ligands Derived from Bicyclic Aminophosphoranes: Obtaining Di- and Trimetallic Iron NitrosyIs Laurence Mordenti, Jean-Louis Roustan,+ and Jean G. Riess" Laboratoire de Chimie Minhale Mol6culaire. Equipe de Recherche Associ6e au CNRS, Universit6 de Nice, Parc Valrose, 06034 Nice-Cedex, France Received December 20, 1982
Bicyclic aminophosphorane 2, PhPH(OCH2CH,)2N, displaces one or two carbonyl groups of Fe(C0)2(N0)2 , to yield P-only-bonded adducts 4 and 5 of the monocyclic open form 1, PhP(OCH,CH,),NH. These adducts further react through their uncoordinated NH sites with [Fe(N0)J2 to yield di- and trimetallic iron nitrosyl compounds 10 and 11 in high yields.
Introduction Polydentate ligands are a means of assembling several metallic centers in the same molecule. Cooperative effects in reactivity and catalysis might be expected from such assemblages.' Particularly attractive in this respect are dissymetric ligands that display donor sites of strongly distinctive character.2 This is the situation in the open eight-membered cyclic aminophosphane tautomer 1 of bicyclic phosphorane 2.3 In this paper we report the synthesis of di- and trimetallic species resulting from the sequential coordination of the P- and N-donor sites of ligand 1 on two distinct metallic centers.
Our choice of iron nitrosyls as substrates to test the assembling abilities of these ligands was also motivated by the potential interest of such derivatives in homogenous ~atalysis,'~ especially in relation to the environmental control of the nitric oxides produced in fossil fuel combustion. Mixed nitrosyl/carbonyl derivatives might also be useful in Fischer-Tropsch and water-gas shift reactions, in which iron carbonyl compounds have already been proven to be active.15 Finally, there seems to be little information available yet on polynuclear nitrosylmetal compounds.16
Experimental Section
2
'
Compounds such as 1 have already proven to be versatile ligands, capable of behaving as P-bonded monodentate or as chelated bidentate ligand^.^^^ It was also shown that in the complexes previously investigated, these ligands were prone to facile subsequent reactions that led to marked alterations of their molecular architecture. In particular, deprotonation at nitrogen afforded the first compounds in which directly bonded phosphorus and oxygen atoms? or phosphorus and nitrogen atoms,' were both coordinated to the same transition metal. The reversible transfer of the phenyl group from phosphorus to a coordinated iron atom was also observed? while the reaction of 2 with Cp(CO),M~Mo(CO),Cpgave several products, one of them resulting from the unusual substitution of a carbonyl ligand with retention of the metal-metal triple bond.g To test the bridging ability of ligand 1, it was desirable to select metallic fragments that when bonded to phosphorus, should not favor such transformations. Our current interest in iron nitrosyl complexes1° led us to select iron dinitrosyl dicarbonyl, Fe(C0)2(N0)2,3, as a likely candidate to meet this criterion. In the light of previous results,11J2stable compounds resulting from its reactions with 1 were expected to arise from the coordination of the P-donor site. Furthermore, according to its documented reactivity in substitution reactions,"J3 the sequential coordination of one and then two molecules of 1 could be contemplated to afford substrates for the synthesis of di- and trimetallic derivatives. On leave from the University of Ottawa, Department of Chemistry, 365 Nicholas, Ontario, K1N 9B4 Ontario, Canada, during the academic year 1980-1981.
All the reactions were carried out under an argon atmosphere or under vacuum. Standard techniques for the handling of airand moisture-sensitive materials were used throughout. NMR spectra were recorded on a Bruker WH-90 spectrometer operating (1) Muetterties, E. L. Bull SOC.Chim Belg. 1975,84,959. Muetterties, E. L.; Rhodin, T. N.; Band, E.;Brucker, C. F.; Pretzer, W. R. Chem. Reu. 1979, 79, 91. Muetterties, E. L.; Stein, J. Ibid. 1979, 79, 479. (2) Savignac, M.; Cadiot, P.; Mathey, F. Inorg. C h i n . Acta 1980,45, L43. Schore, N. E.; Hope, H. J. Am. Chem. SOC.1980,102,4251. Demerseman, B.; Dixneuf, P. H. J. Organornet. Chem. 1981,210, C20. Farr, J. P.; Olmstead, M. M.; Hunt, C. H.; Balch, A. L. Inorg. Chem. 1981,20, 1182. Balch, A. L. "Reactivity of Metal-Metals Bonds";Chisholm M. H., Ed.; American Chemical Society Washington, DC 1981; ACS Symp. Ser. Chapter 8, p 167 and references therein. (3) Ho~~alla, D.; Brazier, J. F.; Sanchez, M.; Wolf, R. Tetrahedron Lett. 1972, 2969. (4) Pradat, C.; Riess, J. G.; Bondoux, D.; Mentzen, B. F.; Tkatchenko, I.; Houalla, D. J.Am. Chem. SOC.1979,101,2234. Bondoux, D.; Mentzen, B. F.; Tkatchenko, I. Inorg. Chem. 1981, 20, 839. (5) Wachter, J.; Jeanneaux, F.; Riess, J. G. Inorg. Chem. 1980,19,2169. (6) Wachter, J.; Mentzen, B. F., Riess, J. G. Angew, Chem., Int. Ed. Engl. 1981,20, 284. (7) Jeanneaux, F.; Grand, A.; Riess, J. G. J. Am. Chem. SOC.1981,103, 4272. (8)Vierling, P.; Riess, J. G.; Grand, A. J. Am. Chem. SOC.1981, 103, 2466. (9)Wachter, J.; Mitschler, A.; Riess, J. G. J.Am. Chem. SOC. 1981,103, 2121. (10) Roustan, J. L. A.; Merour, J. Y., Forgues, F. A. J. Organornet. Chem. 1980,186, C23. (11) Morris, D. E.; Basolo, F. J. Am. Chem. SOC.1968, 90,2531, 2536. (12) Ross, E. D.; Dobson, G. R. Inorg. Chem. 1967,6, 1256. (13) McBride, D. W. Stafford, S. L.; Stone, F. G. A. Inorg. Chem. 1962, 1, 386. (14) Eisenberg, R.; Meyer, C. D. Acc. Chem. Res. 1975, 8, 26. McCleverty, J. A. Chem. Rev. 1979, 79, 53. (15) Masters, C. Adu. Organornet. Chem. 1976, 17, 61. Rofer de Poorter, C. K. Chem. Reu. 1981,81,447. Herrmann, W. A. Angew. Chem., Int. Ed. Engl. 1982, 21, 117. (16) Connelly, N. G. Inorg. Chim. Acta Reo. 1972, 6,47. Kirtley, S. W.; Chanton, J. P.; Love, R. A.; Tipton, D. L.; Sorrell, T. N.; Bau, R. J. Am. Chem. SOC.1980,102,3451. Fjare, D. E.; Gladfelter, W. L. Ibid. 1981, 103, 1572.
0276-7333/83/2302-0843$01.5~/0 0 1983 American Chemical Society
844
Organometallics, Vol. 2, No. 7, 1983
Mordenti, Roustan, a n d Riess
Table I. IR Dataa for Mono- and Polymetallic Iron Nitrosyl Complexes Fe(NO),(CO)(1) ( 4 ) Fe(No)z(CO)[P(C,H,),l ( 6 ) Fe(NO),(1), (5)
2 0 2 0 (s) 2 0 2 0 (s) 2 0 0 9 (s)
1 7 6 5 (s), 1 7 3 0 (vs) 1 7 6 0 (s), 1 7 2 0 (vs) 1 7 6 4 (s), 1 7 2 2 (vs) 1 7 2 5 (s), 1 6 7 5 (vs) 1 7 0 5 (s), 1 6 6 0 (vs)
3 4 0 0 (w) 3400(w)
CH,Cl, KBr
c2c4
3400(w) 3 3 0 0 (w)
Fe(NO),[P(C,H,),I,
(7) Fe(NO),(CO){(l)[Fe(NO),I]} (10)
Fe(NO), CC 1) [Fe(NO),II), (11) a v
in cm-'.
2 0 2 5 (s)
1 7 2 4 (s), 1 6 7 9 (vs) 1 8 0 0 (s), 1 7 7 0 (s) 1 7 4 0 (sh), 1 7 3 0 (vs) 1800 (sh), 1 7 9 0 (s), 1 7 2 5 (vs) 1 8 0 0 (s, 1 7 3 5 (vs), 1 6 8 5 (s) 1 7 8 5 (s), 1 7 2 5 (vs), 1 6 8 5 (vs)
s = strong; vs = very strong; w = weak; sh = shoulder.
at 36.44 MHz for phosphorus (85% H3P04external reference); positive chemical shifts were taken downfield from the reference. Infrared spectra were obtained on a Perkin-Elmer 577 spectrometer calibrated with polystyrene film. Elemental analyses were performed by the Service Central d'Analyses du CNRS. Mass spectra were obtained on a NERMAG-R-1010 and on a 7070E V.G. analytical mass spectrometer. Melting points were recorded in sealed capillary tubes under argon. Solvents were purified before use: CHpC12was distilled over P205,T H F over benzophenone/Na, and hexane, heptane, and toluene over Na/K. Bicyclophosphorane 2,3 Fe(C0)2(N0)2 (3)," and [Fe(NO),I], (8)l8J9were prepared as described in the literature. Fe(NO),(CO)[PhP(OCH2CH,),NH] (4). A solution of the bicyclic phosphorane 2 (2.44 g, 1.15 X lo-, mol) and iron dinitrosyl dicarbonyl (3 2.75 g, 1.6 X lo-, mol) in 100 mL of hexane was maintained a t 60 "C for 8 h with stirring. After being cooled to room temperature, the solution was separated by filtration from the solid that had formed. The filtrate was evaporated to dryness under vacuum. The residual red oil was purified by column chromatography on silica mounted in CH2C12.The product was eluted with acetone-dichloromethane (1:9). The red oil obtained after complete removal of the solvent under vacuum was redissolved in heptane. After 3 days at -40 "C, 4 was obtained as red needles (2.4 g, 6 0 % ) : mp 35-40 "C; mass spectrum (chemical ionization, NH,), [rn + 1' 356. Anal. Calcd for C11HlSN305PFe: C, 37.2; H, 3.95; N, 11.83; P, 8.74. Found: C, 37.1; H, 3.94; N, 11.96; P. 8.54.
Fe(NO),[PhP(OCH,CH,),NH], (5). A solution of the bicyclic phosphorane 2 (8.79 g, 4.2 X lo-, mol) and iron dinitrosyl dicarbonyl (3,3.1 g, 1.8 X lo-, mol) in 200 mL of toluene was heated at reflux with stirring. IR monitoring indicated no further change in the composition of the solution after 6 h. The solvent was removed under vacuum, and the reddish solid residue was washed with 3 X 30 mL of pentane. Recrystallization in dichloromethane-heptane ( ~ 4 afforded ) 5 as a microcrystalline dark orange solid (9.3 g, 96%): mp 119-120 "C; mass spectrum (chemical ionization, NH3), [m + 11' 539. Anal. Calcd for C20H2sN406P,Fe:C, 44.60; H, 5.20; N, 10.40; P, 11.52. Found: C, 44.59; H, 5.22; N, 9.66; P, 10.80. Bimetallic Adduct Fe(NO)2(CO)[PhP(OCH,CHz)zN(H)Fe(NO),I] (10). Iron dinitrosyl iodide dimer 8 (0.163 g, 0.34 X mol) in heptane (10 mL) was added dropwise to a stirred solution of complex 4 (0.238 g, 0.67 X mol) in heptane (15 mL) at room temperature. A precipitate formed instantaneously. The solid was separated and washed repeatedly with hexane to afford 10 as a brown microcrystalline powder (0.37 g, 90%): mp 105-110 "C; mass spectrum (chemical ionization, NH3), (Fe(NO)2(CO)[PhE'(OCH,CH,)2NH](H)])f as the heaviest fragment [m]' 356. Anal. Calcd for C11H14N507PFe21:C, 22.07; H, 2.34; N, 11.70. Found: C, 22.53; H, 2.34; N, 11.70. Trimetallic Adduct Fe(N0)2[PhP(OCH2CH2)2N(H)Femol) in CH2Clz(15 (NO),I], (11). Dimer 8 (0.6 g, 1.23 X (17) King, R. B. "OrganometallicSynthesis"; Academic Press: New York, 1965fVol. 1, p 167. (18)Haymore, B.; Feltham, R. D. Inorg. Synth. 1973, 14, 82. (19) Hieber, W.; Anderson, J. S. 2.Anorg. Allg. Chem. 1933,211, 132.
( 1 ) = PhP( OCH,CH,),NH.
C C
13
CH,Cl, KBr
C C
c*c4
13
CH,Cl,
C
THF CH,Cl, THF
C C
C
This work.
mL) was added dropwise to a solution of complex 5 (0.66 g, 1.22 X mol) in CH2Clz(30 d) at room temperature with magnetic stirring. Removal of the solvent under vacuum yielded a black microcrystalline air-sensitive solid that was washed repeatedly with pentane and dried under vacuum (1.05 g, 8 5 % ) ;mp 100 OC dec. The presence of CHzC12in the solid was indicated in the mass spectrum by the presence of three peaks at [m]' 84,86, and 88 in a ratio close to 9:6:LZ0 Anal. Calcd for CzoH~N801J'zFe31zCHzC12: C, 22.72; H, 2.71; N, 10.10; Fe, 15.15. Found: C, 22.10; H, 2.50; N, 9.90; Fe, 15.40.
Results and Discussion (1) Selective Complexation of the Phosphorus Donor Site of Ligand l. T h e reaction of Fe(C0)2(N0)z (3) i n hexane at 60 "C with slightly less than 1 molar equiv of bicyclophosphorane 2 affords the product of monosubstitution 4, which is soluble. It was isolated in 60% yield as low melting (- 35 "C) red needles. Small quantities Fe(CO),(VO),
3
7Fe(COl~NO)z[PhP(OCH2CH~lzNHI 4 Fe~NOI,[PhP(OCH,CH21,"12
5
of t h e disubstituted derivative 5 were also formed and precipitated out during t h e reaction. The latter product 5 is more conveniently prepared (in 96% yield) b y reacting 3 with an excess of 2 in refluxing toluene. IR monitoring revealed t h e intermediate formation of the monosubstituted derivative 4 during the course of t h e reaction. Ele m e n t a l analysis and mass spectra (chemical ionization with ammonia or isobutylene) a r e consistent with t h e proposed formulations. The 31PNMR spectra consist of single peaks at 193 and 204 ppm for 4 and 5 respectively (solvent CH2C12). T h e s e values are within the 210-160p p m range usually f o u n d for the resonance of t h e metalbonded phosphorus atom of t h e open cyclophosphane form 1: strongly indicating that in 4 and 5 t h e phosphorus atom of 1 is bonded to iron. IR spectroscopy is frequently used to assess t h e electronic properties of ligandsz1and to infer t h e bonding mode of NO ligands i n nitrosyl complexes.22 T h e v(C0) and v ( N 0 ) values of 4 and 5 (Table I) a r e very close to those of the triphenylphosphane-substitutedanalogues 6 and 7 that contain linear T h i s could reflect a similarity in the donor/acceptor properties of cyclophosphane 1 and (20) "Practical Mass Spectrometry. A Contemporary Introduction", Middletich, B. S., Ed.; Plenum Press: New York, 1982; p 4. (21) Tolman, C. A. J. Am. Chem. SOC.1970, 92, 2953. (22) Haymore, B. L.; Ibers, J. A. Inorg. Chern. 1975,14, 3060. (23) Albano, V. G.; Araneo, A.; Bellon, P. L.; Ciani, G.; Manassero, M. J. Organornet. Chem. 1974, 67, 413.
PIN Ligands Derived from Bicyclic Aminophosphoranes
Organometallics, Vol. 2, No. 7, 1983 845
triphenylphosphane and could also indicate that the same separately, all attempts to induce a clean crystallization linear arrangements and bonding modes of NO exist in from this solution were unsuccessful. However, complete both 4 and 5. One should not expect any further interremoval of the solvent left behind a dark microcrystalline action between the metal and the amino sites, since the solid, insoluble in hexane, unlike dimer 8, one of the initial iron is already coordinatively saturated by the phosphorus components of the solution. Elemental analysis is condonor site of 1. In agreement with this, concentrated sistent with the formation of the trimetallic complex 11, solutions of 4 exhibit a weak and broad absorption cenretaining a solvent molecule in the solid. The 31PNNR tered at 3400 cm-l, indicative of an uncoordinated secspectra of 11 in CHzClzconsists of a single and broad peak ondary amine." Such a vibration was not detected in the at 212-213 ppm (depending upon dilution), about 9 ppm spectra of 5 in solution; two weak and sharp absorptions downfield from the phosphorus resonance of 5 in the same were however present at 3400 and 3300 cm-l, in the spectra solvent. The same result was obtained when the solution of 5 taken in KBr or Nujol. The appearance of more than of 5 and 8 in a 1:l ratio was prepared directly in the NMR one vibration assignable to a v(NH) mode in the solid-state tube. The modification of the d(P) values resulting from spectra of secondary amines is not uncommon" and might the complexation of the nitrogens of 4 and 5 were thus of reflect the occurrence of intermolecular interactions comparable magnitude. Three v(N0) were present at 1800, through hydrogen bonds in the solid-state structure of 5. 1735, and 1685 cm-l, in the IR spectra of trimetallic 11 (in (2) Complexation of the Nitrogen-Donor Sites of CHzC12),with the absorption a t 1800 cm-' only slightly Complexes 4 and 5. The ready availability of distronger than the one at 1685 cm-l, both of them being starting from nitrosyliron iodide dimer 8, [Fe(NO)zI]2119 weaker than the 1735-cm-' vibration. Fe(N0)2(C0)2and its documented reactivity toward nitONR rogenous bases25@were the incentives to study its reactions with complexes 4 and 5. Reaction at room temperature of the monosubstituted derivative 4 in hexane solution with 0.5 molar equiv of dimer 8 in the same solvent resulted in the formation of the bimetallic adduct 10, which precipitated out as a brown 10 \ microcrystalline solid. Its 31PNMR spectrum in CH2C12 exhibits a single peak at 202.4 ppm, about 10 ppm downfield from the phosphorus resonance of 4 in which the amino sites were not coordinated. The IR spectrum of 10 in CH2C12shows one v ( C 0 ) (2025 cm-') and four v(N0) (1800, 1775, 1740 (sh), and 1730 cm-') vibrations originating from the Fe(CO)(NO),-P and Fe(I)(N0)2-NH fragments. For comparison, (piperidine)Fe(NO),Br has 11 A weak vibration at absorptions at 1791 and 1731 3190 cm-' present only in the KBr spectra was assigned Paralleling the behavior of bimetallic 10 in THF, partial to the coordinated NH on the basis of previous resuits with decomplexation of the Fe(NO),I unit from the N-donor neutral monometallic molybdenum chelate complexe~.~ sites of 5 was indicated by the disappearance of the abThe solution spectrum is solvent dependent. In THF, sorption at 1800 cm-' in this solvent. although the v(C0) was only marginally affected, in the Interestingly, although complex 5 is moderately air v(N0) region only two strong, broad absorptions were stable in the solid, the trimetallic adduct 11 is highly present at 1790 and 1725 cm-l, the third absorption at 1800 sensitive to molecular oxygen. The reaction resulted in cm-' being weak. This could reflect a competition between the disappearance of the IR absorptions characteristic of T H F and the amino sites of 4 for coordinating the Fe(Nall the NO ligands (and particularly those associated with 0)21fragments, an indication that the iron-nitrogen bond the Fe(NO),(l), subunit) and the appearance of a strong in 10 might be rather labile. Modification of the IR spectra absorption centered at 1380 cm-', in the region where of dimer 8, when changing from CH2C12(v(N0) = 1810 and absorptions of NOz ligands are expected.28 This reaction 1770 cm-') to T H F (v(N0) = 1780 and 1720 cm-l), further is under active study. substantiates the occurrence of interactions between this In conclusion, the open form 1 of bicyclophosphorane solvent and the Fe(N0)21fragmentqZ7 2 can serve as an assemblage between two metallic fragDimer 8 also reacts with 5. An equimolecular mixture ments. On the basis of the principles that led to the of 8 and 5 was prepared in CHZClz. Although 5 and 8 are synthesis of di- and trimetallic complexes 10 and 11 in good tractable compounds that crystallize easily when taken yields, it is likely that a larger variety of polymetallics of this type can be constructed by a systematic variation of the nature of the metallic centers attached to the P- and (24) Bellamy, L. J. "The Infra-Red Spectra of Complex Molecules"; Methuen: London. 1960. N-donor sites of 1. (25) Crow, J. P.ICullen, W. R.; Herring, F. g.; Sams, J. R.; Tapping, R. L. Inorg. Chem. 1971,10, 1616. (26) Hieber, W.; Kramolowski, R. 2. Anorg. Allg. Chem. 1963,321,94. (27) [(ON)2FeCl]2,the chloro analogue of dimer 8, was already known to react in THF to give solutions with v(N0) close to that of 8 in the same solvent: Ballivet-Tkatchenko,D.; Riveccie, M.; El Murr, N. J.Am. Chem. SOC.1979, 101, 2763.
Registry No. 2, 57680-64-5;3, 13682-74-1; 4, 84988-35-2; 5, 84988-36-3; 8, 15002-08-1; 10, 84988-37-4; 11, 84988-38-5. (28) Nakamoto, K. 'Infrared and Raman Spectra of Inorganic and Coordination Compounds", 3rd ed.; Wiley: New York, 1978; pp 220-225.
